Hardening casein artificial fibers with titanium, zirconium or tin salts



Patented Sept. 11, 1951 HABDENING CASEIN ARTIFICIAL FIBERS WITH TITANIUM, ZIRCONIUM OB- TIN SALTS John F. Corwin, Unadilla, John B. Calhoun, Bainbridge, and Thomas M. Bum, Unadilla, N. Y.. assignors to The Borden Company, New York,

N. Y., a corporation of New Jersey No Drawing. Application January 6, 1948,

Serial No. 820 I 8 Claims. (Cl. 8-1216) 1 I This invention relates to a process for treating artificial fibers and filaments formed with casein,

and to the products produced. In particular.

this invention is directed to a method for producing filamentous structures formed from casein which are curly and wool-like, and which in addition have improved chemical and physical properties.

In the manufacture of artificial filaments and I fibers formed from casein, the ordinary process comprises the steps of dissolving a casein material in an alkali solution, extruding the dissolved casein through a spinneret into an acid coagulating bath to form a plurality of filaments, thereafter passing the bundle, i. e., tow, through subsequent baths which may contain formaldehyde, and finally subjecting the tow to prolonged curing or hardening in a formaldehyde hardening bath. The hardened filaments are then thoroughly washed to remove excess formaldehyde, acid, salts, and the like, and then dried. If desired, they may be cut to a predetermined length impossible to control, resulting in the formation of uneven and streaky yarns and fabrics.

Many attempts have been made to overcome these disadvantages but such attempts have not proven entirely satisfactory. Many of the proposed treatments' do not improve the boil resistance to a satisfactory degree. Other treatments, while they may impart satisfactory resistance to hot dilute acid and alkali solutions, at the same time introduce other objectionable characteristics, such as loss of strength and "tendering." Still other treatments result in a darkening or other permanent discoloration which prohibits the use of the fiber in the formation of textiles having white or light shades. .Furthermore such treatments often produce a harsh or objectionable hand; or sometimes may involve the use of expensive or dangerous chemicals. For example,

it has been suggested that the resistance of casein fiber to acid and alkali boil treatments may be improved by subi ecting the fiber to an acetylation step. In this treatment, the casein fiber is first dried, then treated with ketene or acetic anhydride at elevated temperatures for a period of several hours. Although this treatment may enhance theboil resistance and dyeing properties of the fiber, a substantial percentage of the fiber strength is lost, the fiber becomes yellow, dull and lifeless, and takes on an undesirable scroop. The use of acetic anhydride in the treatment of casein fibers at elevated temperatures is also undesirable because a recovery process is required. and from the operational standpoint elaborate precautions have to be taken to avoid exposure to the irritating and poisonous fumes. In addition, an extra washing and drying step is required, which adds to the cost of processing such The use of sodium nitrite or nitrous acid has also been suggested as a means for improving the boil resistance of casein fiber. This process is unsatisfactory in that the fiber becomes brown in color and also results in a loss in fiber strength.

The use of chromium salts has also been su gested for the after-treatment of casein fibers. Although this process ordinarily producesv fibers which have satisfactory boil resistance without loss in strength, it imparts a permanent bluegreen color to the fiber which is difiicult and usually impossible to mask or neutralize. Such fiber is, therefore, suitable for forming textiles having dark or black shades only.

Other processes for improving the boil resistance and dyeing characteristics of fiber have been suggested, but these have been found either to be ineffective in accomplishing their purpose. impractical, or resulting in an adverse eflfect upon the physical-and chemical properties of the fiber.

should have a relatively high tensile strength;

(e) finally, such filament or fiber should have a rate of dye takeup substantially comparable to that of wool. All of these prerequisites must be met in order to provide artificial casein fibers and filaments having real commercial value. Thus, in accordance with the present invention.

the final product after processing, comprising the artificial filaments and fibers formed from casein. must be subjected to and pass these-standards, hereinafter called "the pentafold test),

It is, therefore, a general obiect of the present invention to provide a process for treating artificial filaments and fibers formed from casein in order to produce productshaving improved physical and chemical properties, thereby overcoming the disadvantages heretofore encountered in the prior art.

It is a further object of this invention to provide a method for treating artificial casein filaments and fibers to produce a final product having enhanced characteristics, including a high resistance to hot dilute acid and alkali solution, improved rate of dye, takeup, retention of a substantial part of the tensile strength of the original fiber. white color, a soft feel, and which final product after treatment acquires a good crimp .with little or no scroop.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The pentaiold test which has been adopted in order to establish a set of standard requirements for the product of the present invention. is as follows: (1) Acid boil resistance Asampleoffibertobetestedisplacedinan acid bath buffered to a pH of 2.5, the bath then being brought to boiling and maintained at boiling temperature for 1% hours. at the end of this, period the fiber is removed from the bath,

' assigned to those fibers which show a gradual variance in properties from an unchanged to a completely disintegrated fiber.

(I) Alkali boil resistance Thisisconductedinamannersimilartothat of the acid boil resistance test, except that the test solution is bufiered at a pH of 8.6, and the time of boil is 1 hour instead of hours. Ratings are assigned to the washed, dried fiber in amanneridenticaltothoseassignedintheacid boil resistance test.

(3) Color it was found that such structures, as a result v The finished fiber is evaluated for color by visual inspection. If the fiber retains a substantially light color which is capable of being dyed t0 pastel shade, especially when co with other fibers such as rayon, wool and the like. then the finished product is passed as satisfactory.

(4) Tensile strength They are then prepared for testing by the standard A S. 'I. M. method, 1948 A. S. T. M. Standards, part 3 (a) Nonmetallic Materials." Standard Method for Testing Rayon Staple Tensile Strength Part A," preferred method fiat bundle, pages 640-643,.sections 24-31 inclusive, except that the bundle is made smaller so that it will be suitable for testing in the ,Scott ZIP-2 Tester. Samples for wet strength testing are soaked for 30 minutes in distilled water at room temperature I prior to testing. The strength figures are reported as grams per denier.

( Due talceup The rate of dye takeup is determined by preparing a dye bath ordinarily used for dyeing wool -fibers and an equivalent amount of the final product, after treatment in accordance with this invention, is immersed in this bath. The rate of dye takeup is then determined by observing the time at which the dye bath becomes exhausted, and comparing this with the rate of dye takeup on wool. The appearance of the dyed fiber also gives a good indication of the rate of dye take up since, if the dye takeup is too high, the fiber will be uneven and mottled in appearance.

We have now found that these objects may be attained by treating filamentous structures consisting of artificial casein filaments and fibers, after coagulating such structures but prior to drying, by inserting a step comprising subject'- ing said structure to treatment in an aqueous solution of a salt of .im selected from the group consisting of zirconium, titanium, and tin. In addition to providing a product having enhanced chemical and physical characteristics,

of such treatment with these particular metal salts, became curly and acquired wool-like pro- In the now preferred embodiment, the filamentous casein structures are subjected to treatment by the metal salt solutions of the class described at elevated temperatures of between F. and 200 l t, preferably for a period of from 1 to 24 hours, at a pH of 0.8 to 3.0.- The treatment may be conducted either on uncut strands, with or without tension, or on the staple fiber. If desired, there may-be added to the treating bath other salts, such as sodium chloride, sodium sulphate and the like; hardening agents such as formaldehyde; and if necessary, sufilcient acid or acid salts to control the pH within the range of 0.8 to 3.0. The ratio of fiber to bath, including solids, is on a weight basis. preferably in a ratio of from one part of filament or fiber to between 15 to 20 parts of the bath.

The amount of the metallic salt which may be used is within the range of from a 0.5% solution up to saturation. Poor results are obtained using solutions containing less than 0.5% salt concentration. The amount of metallic salt preferably employed in the treating bath was found to be within the range of from 2% to 10% of said salt on a weight basis. Among the-sirconium salts which may be used are, for example, zirconium sulphate, sodium zirccnyl sulphate, potassium zirconyl oxylate, ammonium zirconyl sulphate, and the like. Among the titanium salts which may be employed are titanium basic sulphate, titanium tetrachloride and the like. Among the tin salts which have been found to be satisfactory are stannic chloride, stannic sulphate, stannous chloride, and the like.

Best results have been attained by carrying creaseinthetemperaturen outthstreahnentofthecaselnfiberinthemetal salt bath at elevated temperature, within the range of 120' I". and 200'1'. The efiectiveness of-the reaction of the metallic salt on the protein wasfoundtoincreaseveryrapidlywithaninthenecessary as the increased. m example. at

room temperature the full efiectiveness of the treatment isnot realised even when the fiber leftinthe'metallic salthath 1'01 aperiod of gg i men ioned. the pH range must lie 0.8 to 3.0 in order to attain best results final product. The optimum pH range foundto lie within a ran e of 1.0 to If the pH of the bath is lower than 0.8, the strength of the resulting fiber is reduced.

hi h

The following-examples a...- given by way of illustratioln Unless otherwise stated, the parts herein recited are in parts by weight.

Example 1 Acid precipitated casein was dissolved with the aid of 2.1% of caustic soda to a'solids content of about and then extruded through a spinneretinto a sulfuric acid-sodium sulphate coagulating bath,and the bundle of filaments then passed through a saline setting bath with concurrent stretching, and thereafter hardened overnight in a bath containing sodium sulphate and formaldehyde. The hardened filaments were then squeezed to remove excess hardening bath, stapled to A" length, and the unwashed stapled fiber treated in the following bath for 2% hours at 165 1''. with a'bath-to-fiber ratio of 17:1 by weight based upon the dry weight of the fiber, at a pH of 1.6:

Per cent Sodium xirconyl sulphate 5.7 I'lormalin 6.7 Water 88.6

1 After treating, the fiber was centrifuged to re- An is precipitated casein was dispersed with I the aid of 2.3% of caustic soda to asolids content of about 20%. and then extruded through Pull effectiveness is attained at 160 a spinneret into an acid-salt coa ulating bath. Thebundle of filaments was then passed through a saline setting bath with concurrent stretching. and then hardened for 3 hours in a bath containing sodium sulphate and formaldehyde. The

hardened filaments were then squeezed between rolls to remove excess hardening bath. stapled to 2' length, and the staple fiber then treated in the following bath for 2% hours at 170-175 1"., at a pH of 1.1:

' Per cent Stannic chloride 6.3 l'ormalin 6.3 Water 87.4

boilresistanceratingsintherarig'eof8to9for both the alkali boil and the/acid boil tests. The finished fiber was substantially white in color, soft and wool to the touch, and possessed excellent crimp.

mm. a

Casein fiber was prepared, extruded and treated in a manner similar to Example 2, except that the bath containing the stannic chloride was replaced by the following bath. The pH of this bath was 1.3, and the temperature was approximately 1*.ior 3 hours:

Per cent Basic titanium sulphate 6.3 Formalin 6.3 Water 87.4

Example 4 Casein fiber was prepared. extruded and treated in a manner similar to Example 2, except that the bath containing stannic chloride was replaced by the following bath, with sufficient sulfuric acid added to adjust the pH to 1.65:

Per cent Potassium zirconyl oxylate 6.3 Formalin 6.3 Water 87.4

The fiber was treated in the bath at F. for

2% hours. After treating, the fiber was centrifuged. washed. oiled and dried. When tested the fiber was found tohave an alkali boil rating of 3, and an acid boil rating between 2 and 3. The finished fiber was substantially white in color, soft and wooly to the touch, and possessed ex cellent crimp.

Example 5 Casein fiber was prepared, extruded and treated in a manner similar to Example 2, except that 7 the bath containing stanni chloride was replaced by the following bath having a pH of 1.7:

Sodium zirconyl sulphate 5.7 Formalin 5.7 Water 88.6

The fiber was treated in the bath at 135 F. for 7 hours. After treating, the fiber was centrifuged, washed, oiled and dried. When tested the fiber was found to have an alkali boil rating of 3, and an acid boil rating of 2. The finished fiber was white in color, soft and wooly to the touch, and had good crimp.

Example 6 Casein fiber was prepared, extruded and treated in a manner similar to Example 2, except that the bath containing stannic chloride was replaced by the following bath having a pH of 2.0.

Per cent Ammonium zirconyl sulphate 1.25 Formalin 6.25 Water 92.50

Example 7 Casein fiber was prepared, extruded, and

. treated in a manner similar to Example 2. except that the bath containing stannic chloride was replaced by the following bath having a pH of 2.3:

., Per cent Stannous chloride 6.3 Formalin 6.3 Water 87.4

The fiber was treated in the bath for 3 hours at 170 F. After treating, the fiber was centrifuged, washed, oiled, and dried. When tested, the'fiber was found to have an alkali boil rating of 3, and an acid boil rating of 3. The finished fiber was white in color, soft, and wooly to the touch, and had good crimp.

The advantages flowing from the present invention are considerable, some of the advantages being as follows:

The novel metallic salt treatment may be made on fiber in the wet state without the necessity of pre-drying. Furthermore, such treatment, being an aqueous treatment, does not necessitate the use of expensive or dangerous organic chemicals and solvents. nor is there any necessity for a recovery system. The resultant fiber is substantially white in color. The finished product retains a substantial part of its original strength and there is relatively no scroop resulting from such treatment- A wool-like effectis always obtained. The fiber is comparatively resistant to dilute acid and alkali solutions, especially when boiled. Finally, the dyeing properties are enhanced in that the fiber possesses a slower rate of dye takeup, thus enabling the dyeing plant to hours Per cent obtain bright, uniform, level or in admixture with other types of fibers.

Other advantages will be evident from the various applications and uses to which such filaments and fibers may be put.

Since certain changes in carrying out the above process, and certain modifications in the article which embody the invention may be made without departing from its scope, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

We claim:

1. A process for producing an artificial filament from. casein having high resistance to hot acid and alkali treatment, light color, good tensile strength, and even dyeing properties,- utilizing the .initial steps of dissolving casein in an alkaline liquid, delivering a stream of the said casein solution into anacid coagulating bath.

and hardening the coagulated casein in a second bath containing at least formaldehyde, comprising the inventive step of treating the coagulated and hardened fibers from thehardening bath, without intermediate drying. by the application thereto of an aqueous solution of a salt of a metal selected from the group consisting of titanium, zirconium, and tin in a concentration within "the range between 0.5% and saturation, at a bath pH within the range between 0.8 and 3' and 'at a temperature between F. and,200' F.

2. A process for producing an artificial filament from casein having high resistance to hot acid and alkali treatment, light color, good tensile strength, and even dyeing properties, utilizing the initial steps of dissolving casein in an alkaline 11quid,- delivering a stream of the said casein solution into an acid coagulating bath, and hardening the coagulated casein in a second bath containing at least formaldehyde, comprising the inventive step of treating the coagulated and hardened fibers from the hardening bath, without intermediate drying, by the application thereto of an aqueous solution of a titanium salt in a concentration within the range between 2% and 10%, at a bath pH within the range between containing at least formaldehyde, comprising the inventive step of treating the coagulated and hardened fibers from the hardening bath. without intermediate drying. by the application thereto of an aqueous solution of a salt of a metal selected from the group consisting of titanium, zirconium, and tin in a concentration within the range between 0.5% and saturation. at a bath pH within the range between 0.8 and 3 and at a temperature between 120 Fjand 200 F.. and thereafter dyeing the filament to a light color.

4. a process for producing an artificial'filament shades, either aione.

from casein having high resistance to hot acid and alkali treatment, light color, good tensile strength, and even dyeing properties, utilizing the initial steps of dissolving casein in an alkaline liquid. delivering a stream oi the said casein solution into an acid coagulating bath, and hardening the coagulated casein in a second bath containing at least formaldehyde, comprising the inventive step of treating the coaaulated and hardened fibers from the hardening bath, without intermediate drying, by the application thereto oi an aqueous solution of titanium sulfate in a concentration within the range between 2% and 10%, at a bath pH within the range between 0.8 and 3 and at a temperature between 120 F. and 200 F.

5. A process for producing an artificial filagames meat from casein having high resistance to hot acid and alkali treatment, light color, good tensile strength, and even dyeing properties, utilizing the initial steps of dissolving casein in an alkaline liquid,delivering a stream of the said casein solution into an acid coagulating bath, and hardening the coagulated casein in a second bath containing at least formaldehyde, comprising the inventive step of treating the coagulated and hardened fibers from the hardening bath, without intermediate drying, by the application thereto 01' an aqueous solution of basic titanium sulfate in a concentration within the range between 2% and 10%, at a bath pH within the range Mtween 0.8 and 3 and at a temperature between 120 F.

I and 200 F.

6. A process for producing an artificial filament from casein having high resistance to hot acid and alkali treatment, light color, good tensile strength, and even dyeing properties, utilizin the initial steps of dissolving casein in an alkaline liquid, delivering a stream of thesaid casein solution into an acid coagulating bath, and hardening the coagulated casein in a second'bath containing at least formaldehyde, comprisin the inventive step of treating the coagulated and hardened fibers from the hardening bath, wtihout intermediate drying, by the application thereto oi an aqueous solution of stannic chloride in a concentration within the range between 2% and 10%, at a bath pH within the range between 0.8 and 3 and at a temperature between 120 F. and 200 F.

7. A process for producing an artificial filament from casein havin high resistance to hot acid 10 I and alkali treatment. light color, good tensil strength, and even dyeing properties, utilizing the initial steps of dissolving casein in an alkaline liquid, delivering a stream of the said casein solu- 8. A process for producing artificial filament i'rom casein having high resistance to hot acid and alkali, treatment, light color, good tensile strength, and even dyeing properties, utilizing the initial steps of dissolving casein in an alkali liquid,-delivering a stream or the said casein solution into an acid coagulating bath, and hardening the coagulated casein in a second bath containing at least formaldehyde, comprising the inventive step 0! treating the coagulated and hardened fibers from the hardening bath, without intermediate drying, by the application thereto of an aqueous solution of sodium zirconyl sulfate in a concentration within the rangebetween 2% and 10%, at a bath pH within the range between 0.8 and 3 and at a temperature between 120F.

and 200 F.

JOHN F. CORWIN. JOHN R. CALHOUN. THOMAS lllL- BUZZO.

REFERENCES CIIZED The following references are of record in the file oi this patent:

UNITED STATES PATENTS Number Name Date 1,717,483 White June 18, 1929 2,294,384 Champion Sept. 1, 1942 2,316,057 Doser et al. Apr. 6, 1943 2,328,431 Doser et a] Aug. 31, 1943 2,339,408 Jacokes et al Jan. 18, 1944 FOREIGN PATENTS Number Country Date 4,457 Great Britain 1915 1 12 Certificate of Correction Patent No. 2,507,184 September 11, 1951 JOHN F.- conwm ET AL It is herebg'e certified that error appears in the fprinted specification of the above num red patent requlring correction as ollows:

Column 1, lihe 2, for with read from; line 30, for Other read Such;

column 2 line 38, for of second occurrence, read or; column 9, line 44, for wtihout read without; coiumn 10, lines 20 and 21, for alkali read alkaline;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in' the Patent Oflice.

'Signed and sealed this 25th day" of December, A. D, 1951.

reforms F. MURPHY, 1

Assistant Commissioner of Patenta. 

1. A PROCESS FOR PRODUCING AN ARTIFICIAL FILAMENT FROM CASEIN HAVING HIGH RESISTANCE TO HOT ACID AND ALKALI TREATMENT, LIGHT COLOR, GOOD TENSILE STRENGTH, AND EVEN DYEING PROPERTIES, UTILIZING THE INITIAL STEPS OF DISSOLVING CASEIN IN AN ALKALINE LIQUID, DELIVERING A STREAM OF THE SAID CASEIN SOLUTION INTO AN ACID COAGULATING BATH, AND HARDENING THE COAGULATED CASEIN IN A SECOND BATH CONTAINING AT LEAST FORMALDEHYDE, COMPRISING THE INVENTIVE STEP OF TREATING THE COAGULATED AND HARDENED FIBERS FROM THE HARDENING BATH, WITHOUT INTERMEDIATE DRYING, BY THE APPLICATION THERETO OF AN AQUEOUS SOLUTION OF A SALT OF A METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, ZIRCONIUM, AND TIN IN A CONCENTRATION WITHIN THE RANGE BETWEEN 0.5%, AND SATURATION, AT A BATH PH WITHIN THE RANGE BETWEEN 0.8 AND 3 AND AT A TEMPERATURE BETWEEN 120* F. AND 200* F. 